Linux

How do you determine the missing security patches on a Linux Server, I think in Solaris you could use showrev -p but unsure of the Linux alternative, or any tool to do this?

You're assuming security patches work in an analogous way on a non-solaris OS, which they probably don't. In any case Linux is only a kernel, so the answers can be completely different depending on which distro -- so, which distro?

Red Hat Linux Enterprise release 4 and another box running release 5 so solutions for both would be great.

Regards

In Linux, in general, there are not "patches" per se. Everything is a package, and if you need to get from foobar-1.25.01 to foobar-1.28.03 this is not a patch but rather an upgrade.

If you would like to see what packages you have installed, rpm -qa will show you.

The best way to see what patches you need would be to use some tool like Satellite Server or a subscription to RHN for a Red Hat machine.